The Joy of Cooking

"I have prepared my sister's tongue,..."

The speaker uses metonymy in the poem to characterize the speaker's regards to siblings, in the case irate.  The tongue represents the sister, pointing out the fact that she is probably very bold, verbose, and annoyingly chatty.  The act of cutting off the tongue and cooking it reveals anger and scorn.  The heart, which represents the brother, is said to be cold, indicating that this guy is probably a nasty fellow.  Again, the speaker expresses anger via the metaphor of cooking the heart.  I share similar sentiments.  While I do love dearly my siblings, we are prone to conflict.  There are qualities of each sibling that I don't like.  For example, my brother who is 21 is a bit rude and lacks common courtesy.  My little brother exaggerates to my mother the intensity of a conflict, usually attaching blame to my side.  I do not like these things.  I, though, probably won't cook any of their body parts.  I really only know how to use the microwave.